Which acid is an organic compound and a form of vitamin B3?

Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It has the formula C6H5NO2 and belongs to the group of the pyridinecarboxylic acid.

Niacin is obtained in the diet from a variety of whole and processed foods, with highest contents in fortified packaged foods, tuna, some vegetable and other animal sources. Some countries require its addition to grains. Supplemental niacin is primarily used to treat high blood cholesterol and pellagra (niacin deficiency). Not enough niacin can cause nausea, skin and mouth lesions, anemia, headaches, and tiredness. This lack of niacin may also be observed in pandemic deficiency diseases, which are caused by a lack of five crucial vitamins (niacin, vitamin C, thiamin, vitamin D, and vitamin A) and are usually found in areas of widespread poverty and malnutrition.